I seem to remember someone here on this list trying this quad pipes on his 135i. He said it choked the performance bc they are only designed for the 125i motor. ??? It wasn't too long ago he posted about that. I thought he took the car back the next day for his old OE exhuast and money back!

I heard of some shop near Hanover(?) that also does quads... but they charge over 2,500 euros for the rear section. Exhaust pipes and diffuser. Thats way too rich for my blood!